JACoW is a publisher in Geneva, Switzerland that publishes the proceedings of accelerator conferences held around the world by an international collaboration of editors.
@inproceedings{colizzi:cyclotrons2022-webo05,
author = {I. Colizzi and C. Baumgarten and A.L. Gabard and R. Künzi and A.L. Lomax and V. Maradia and D. Meer and S. Psoroulas and D.C. Weber},
% author = {I. Colizzi and C. Baumgarten and A.L. Gabard and R. Künzi and A.L. Lomax and V. Maradia and others},
% author = {I. Colizzi and others},
title = {{Upgrade of a Clinical Facility to Achieve a High Transmission and Gantry Angle-Independent Flash Tune}},
% booktitle = {Proc. CYCLOTRONS'22},
booktitle = {Proc. 23rd Int. Conf. Cyclotrons Appl. (CYCLOTRONS'22)},
pages = {191--195},
paper = {WEBO05},
language = {english},
keywords = {proton, cyclotron, simulation, experiment, radiation},
venue = {Beijing, China},
series = {International Conference on Cyclotrons and their Applications},
number = {23},
publisher = {JACoW Publishing, Geneva, Switzerland},
month = {10},
year = {2023},
issn = {2673-5482},
isbn = {978-3-95450-212-7},
doi = {10.18429/JACoW-CYCLOTRONS2022-WEBO05},
url = {https://jacow.org/cyclotrons2022/papers/webo05.pdf},
abstract = {{In proton therapy, FLASH-RT, irradiation at ultra-high dose rates (>40 Gy/s) that can minimize radiation-induced harm to healthy tissue without reducing its ability to treat tumors, is a topic of great interest. However, in cyclotron-based proton therapy facilities, losses caused by the energy degradation process reduce the transmission to less than 1% for low energies, making it difficult to achieve high dose rates over the clinical range (70-230 MeV). We will demonstrate how an already existing clinical beamline can be converted into a FLASH beamline by beam optic changes only. To achieve maximum transmission, we have developed a new optics that transports the undegraded 250 MeV beam from the cyclotron to the isocenter. However, this has asymmetric emittance in the transverse planes, leading to gantry angle-dependent beam characteristics at the patient. Particle transport has been simulated with MINT (in-house matrix multiplication transport program with Monte Carlo simulations for scattering effects) and benchmarked with beam profile measurements. We used the method of σ matrix matching (M. Benedikt et al. 1997) to achieve gantry angle-independent optics. MINT simulations and beam profile measurements showed a good agreement, and with FLASH optics, we experimentally achieved almost 90% transmission at the patient, translating to a maximum current of 720 nA (>9000 Gy/s). Further, we demonstrate that using the matrix matching optimization criteria together with fine-tuning of the magnets, we could achieve gantry angle-independent beam profiles at the patient location. In conclusion, we demonstrated how an already existing cyclotron-based proton gantry can be adapted to achieve ultra-high dose rates at 250 MeV, enabling investigations of FLASH radiotherapy with protons. Since most of the modifications are performed on the beam optics, it is entirely transparent to clinical operations, making the method transferable to other facilities.}},
}